Mobile communication devices have become increasingly common in current society for providing wireless communication services. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from being pure communication tools into sophisticated mobile multimedia centers that enable enhanced user experiences.
The redefined user experience requires higher data rates offered by wireless communication technologies, such as long-term evolution (LTE). Particularly in light of carrier aggregation (CA) schemes supported by modern cellular communications networks, a mobile communication device can be configured to simultaneously transmit an outgoing radio frequency (RF) signal(s) in multiple uplink frequency bands, while receiving an incoming RF signal(s) in multiple downlink frequency bands.
To achieve the higher data rates and desirable coverage range, the mobile communication device typically employs a power amplifier(s) to increase output power of the outgoing RF signal(s) to maintain sufficient energy per bit and/or desirable signal-to-noise ratio (SNR). Notably, a higher peak associated with the outgoing RF signal(s) can cause the power amplifier(s) to move toward compression that can lead to undesirable out-of-band spectral regrowth and in-band distortion. As such, it may be necessary to bias the power amplifier(s) at a desired voltage level such that the power amplifier(s) can operate with improved linearity and efficiency.
The bias voltage is typically provided from a battery in the mobile communication device. Notably, other active components and/or circuits (e.g., microprocessors, memories, transceivers, antennas, etc.) in the mobile communication device are also drawing voltage/current from the battery, particularly when the mobile communication device transmits the outgoing RF signal(s) in a single-transmit (STX) or a dual-transmit (DTX) mode. As a result, the bias voltage received by the power amplifier(s) can decrease over time, thus causing the power amplifier(s) to suffer degraded linearity and efficiency. In this regard, it may be desired to maintain the bias voltage at the desired voltage level regardless of whether the mobile communication device is operating in STX or the DTX mode.